1. Field of the Invention
This invention relates generally to rope cleats, and more particularly to a rotatable cam-type rope cleat having a rotatable cam-type member for selectively locking and releasing a rope drawn through a passageway formed through an attached housing.
2. Brief Description of the Prior Art
A wide range of devices exist for clamping ropes, cables, and the like. These devices facilitate the fastening and tensioning of such ropes and cables between two points or across a load. A cam-type rope cleat holds rope, cable, and the like secure over a large range of tensions through a straightforward operation.
The rope is drawn into the cleat and through a passageway formed between two opposing cams or between a cam and a rope abutment surface disposed transversely opposite thereto. As the rope is drawn into the passageway it is engaged by the toothed gripping surface of the cam (or cams). As the rope is moved in a first direction, the cam rotates and embeds its toothed gripping surface further into the rope. Thus, further movement of the rope, in the first direction., is prevented. However, the rope may be freely pulled through the passageway in a second direction opposite the first direction.
U.S. Pat. No. 4,912,817 (issued to Sandreid) discloses a gripping device for selectively locking and releasing a rope which may be moved over a guide surface. The device includes a frame having a U-shaped cross-section, a lever which is pivotally mounted in the frame and which rotates about an axis passing transversely through the frame. An engaging member is swingably mounted on the lever; the lever may be moved to a locking position or a releasing position by means of an operating handle on which an eccentric, cooperating with the lever, is mounted. The device disclosed is complicated in design and has many moving parts. The design complexity results in reliability and operating difficulty.
U.S. Pat. No. 3,017,678 (issued to Christensen) discloses a cable locking device. The device includes a body member adapted to have one end of a cable secured therein. The opposite free end of the cable is slidably received in a passageway formed in the body and firmly gripped therein by a lever having an eccentric member pivotable towards the free end of the cable. The clamping force imparted by the eccentric member onto the cable is maintained by a lock that secures the lever. A deficiency associated with this device is that the clamping device is not self-locking. The clamping force must be maintained by locking the lever handle so as to compress the eccentric member onto the cable.
U.S. Pat. No. 5,070,805 (issued to Plante) and No. 4,878,270 (issued to Westerkamp) both disclose cam-type clamping devices that engage and clamp a rope or cable passing through the device. In both devices the rope is drawn through a passageway formed between an engaging surface of a cam and a complimentary rope abutment surface. As the rope is drawn into the passageway along a first direction, it spreads the cam away from the complimentary rope abutment surface. As the rope, under tension attempts to escape the cam, the teeth of the cam press more firmly into the rope and the cam grips and compresses the rope with increasing firmness. Eventually, the rope is unable to be more firmly compressed, and no further motion of the cam results. If the rope is pulled in a second direction, opposite to the first direction, then the rope may be disengaged from the engaging surface of the cam thereby allowing the rope to be pulled through the passageway. The deficiency of the disclosed devices is that a quick disengagement of the rope from the cleat cannot be accomplished. The only way to disengage the rope from the cleat device is to pull the rope in the second direction. This is especially cumbersome and inefficient if a significant length of rope has been previously threaded through the passageway.
U.S. Pat. Nos. 3,091,207 (issued to Songer), 4,766,835 and 4,899,423 (both issued to Randall) disclose similar cam-type devices that engage and clamp a rope, cable or similar article. The disclosed devices feature a cam and an opposing rope abutting surface, both mounted onto a platform that is not enclosed in a housing. The rope or cable passes through a passageway formed between the cam and the corresponding rope abutting surface. Since the passageway is not enclosed in a housing, the rope can be accidentally pulled from the passageway, thereby inadvertently releasing the rope or cable from cleat.
Thus, there is a need to provide an improved rope cleat device that does not possess the shortcomings of the presently employed devices. That is, there is a need to provide a cleat that is self-locking, quickly releases the rope from the engaging cam, is simple with a minimum number of moving parts, and wherein accidental release of the rope from the cleat device is prevented.